Midterm 2 Flashcards
Nine Steps in Cavity Preparation
- Outline Form & Initial Depth - outer shape of the preparation
- Primary Resistance Form - internal shape that
prevents fracture of filling or tooth - Primary Retention Form - internal shape that prevents filling from falling out
- Convenience Form - alteration to outline form to permit proper instrumentation
- Removal of Decay
- Pulp Protection if indicated
- Secondary Resistance & Retention Forms
- Cavosurface Finish - finishing of enamel (cavosurface
bevel)
9. Debridement of the Preparation - cleaning of the cavity (toilet)
Six Classifications of Tooth Caries by
Location (ant. or post. & location by
surface)
- Class I: All pit and fissure caries; may be on occlusal surface of premolars and molars; may be on the occlusal two-thirds of the facial or lingual surface of premolars and molars (where ever there is a groove); may be on the lingual surface of anterior
- Class II Proximal Surfaces of Posterior Teeth
- Class III Proximal Surfaces of Anterior Teeth
- Class IV Proximal Surfaces of Anterior Teeth,
Involving the incisal angle - Class V Involves the gingival 1/3 of all Teeth
Facially (buccal/labial) and Lingually - Class VI Caries on cusp tips and incisal edges
REMEMBER!! All Classes, II-VI, are smooth
surface caries. Class I’s are not (pit [fossa]
and fissures [grooves])
Class I Outline Form & Initial Depth
- The facial-lingual width is to be 1mm (measured by
the smallest amalgam condenser) - Extend slightly further into occlusal primary
grooves (slightly up the major grooves) - Maintain the marginal/oblique ridge integrity following the contour of that ridge
- (for amalgam) Must be ½mm into dentin
- must be 1.7-2mm in depth (pulpal floor to cavosurface margin)
Class I Primary Resistance Form
The internal shape must best prevents the fracture of
the filling material and/or the tooth ie. resist the
forces of mastication
Amalgam preparations must extend 0.5mm into
dentin (clinically) on the pulpal floor
At the shallowest portion (the fossa) of the prep, the
pulpal depth must be 1.7- 2mm & .5mm into dentin.
Burr for Class I and Class II Preparations
• Utilize a #1556 carbide bur; crosscut
fissured bur
• 3.8mm cutting length
• enter perpendicular to the occlusal surface so ½-2/3 of
cutting length sinks into preparation
Class I Primary Retention Form
Internal shape that you produce that best prevents the filling material from falling out
F & L walls form right or very slightly acute angles with the pulpal floor
Walls: Enclosing side of a cavity preparation which takes its name according to its adjacent surface
Other examples of retention form may include:
• grooves
• slots
• undercuts
Class I Convenience (Access) Form
Modification of the ideal outline form in order to be able to remove fully all decay or defective tooth structure
Class I Removal of Decay
Excavation of all infected tooth structure using low-speed rotary instruments and spoon excavators
Class I Cavosurface Finish
Cavosurface angle is the angle formed at the junction
of a cut wall and the external surface of the tooth. (The
actual junction is the cavosurface margin)
Proper Finishing of cavosurface margins is determined by filling material and location of the preparation
- Amalgam Restorations are finished as a “butt joint”
(90 degree exit angle) on the occlusal surface with
no bevel
Class I Debridement of the Preparation
TOILET
Flushing out of all debris from the cavity preparation
Final step prior to beginning the restorative phase of the procedure
Summation of Class I
- Confined to central fissure (outline)
- Small major groove extensions (outline)
- Minimum facio-lingual width 1.0mm (outline)
- Preserve uninvolved marginal ridge (outline & resistance)
- Mesial or distal walls 6° taper (resistance)
- Facial and lingual walls parallel or slightly acute (retention)
• Pulpal floor flat (resistance)
➢ Pulpal depth 1.7 – 2.0mm at shallowest point (resistance)
Definition by Numbers of Surface(s)
- SIMPLE: one surface only
- COMPOUND: two surfaces
- COMPLEX: three or more surfaces
• ATYPICAL Three or more surfaces that
always involve the onlaying of
one or more cusps
Matrix Retainer
Open end of retainer always faces towards the gingiva
Class II Outline Form
Maintain uninvolved marginal ridge integrity
Facio-lingual width 1mm; extend into occlusal primary grooves (slightly up the major grooves)
May or MAY NOT see light into embrasures
Tapering form gingivo-occlusal
Gingival extension (must break contact with adjacent tooth)
Diverging occlusogingivally.
Axial wall contour follows the shape of the tooth at the gingival cavosurface margin
Class II Resistance Form
- Pulpal depth 1.7-2mm and .5mm into
Dentin (clinically) - Axial depth 1mm premolars, 1.3mm molars
- Axio-pulpal line angle beveled
- Uninvolved proximal slightly obtuse (6 degrees)
- Flat pulpal and gingival floors
- Axial wall is convex or follows contour of gingival cavo-surface margin
Class II Retention Form
Buccal & lingual walls face each other (proximal box)
Converging slightly towards the occlusal (proximal box)
Facial and lingual walls parallel or tapering (occlusal)
Proximal Box of Class II
• Centered on contact point (outline)
➢ Gingival margin free of contact (outline)
- Facial & lingual margins < 0.25mm open (outline)
- Minimum facio-lingual width 1.0mm (outline)
- Axio-pulpal line angle rounded (resistance)
- Gingival margin planed (margination)
- No unsupported enamel (margination)
- Facial and lingual walls diverge O → G (retention)
- Axial wall minimum 1.0mm O → G (resistance)
• Axial wall follows gingival margin contour (resistance)
➢ Axial depth 1.3mm (molar) or 1.0mm (premolar)
Rubber Dams…WHY?
- Reduces microbial contamination by up to
99% - Most significant reduction is in vicinity of
operator and dental assistant. - Centers for Disease Control & Prevention,
recommends the use of high speed evacuation
and dental dams - Provide patient protection & increases
access, visibility and moisture control - Prevents aspiration or swallowing of foreign
bodies
AN ULTIMATE TIME SAVINGS OF 40-50%
Rubber Dam Isolation
- Isolation of your working field is accomplished through use of a rubber dam
- Keeps your working area free of debris and saliva
- moisture control (saliva, blood, sulcular fluids)
- retraction
- soft tissue protection
- to improve vision
- absolutely mandatory for all bonded restorations as moisture adversely affects retention and permanence in bonded restoration
Methods of Controlling the Operating Field
DRUGS;
• antisialogogues: not routinely used for operative procedures
• atropine sulfate: .25-.50mg 2 hrs prior to procedure
• belladonnas: 15mg 2 hrs prior to procedure
• scopalamine: 0.4mg 1/2 hr prior to procedure
• valium: 5 - 10mg 1 hr prior to procedure
- local anesthetics:
- lidocaine: anesthetic relax patient reducing salivary flow
Other Necessary Tools for Operation
• Bibulous paper
• Cotton rolls: block duct openings (Parotid, Sublingual)
-must be changed as often as necessary to keep field dry based on patient’s salivary flow
• Vacuum devices:
- hi-speed evacuation
- saliva ejectors
• Rubber dam
The Rubber Dam Instruments
Youngs Frame (Nylon only in Pre-clinic Operative)
Rubber dam sheets: are provided in 5x5 and 6x6 inch squares
Rubber dam punch: used to punch holes of various diameters according to class of tooth
- Holes should be 1.5- 2.0mm apart: too close
together causes rips; too far apart causes bunching
Rubber dam clamps (retainers): used to anchor the dam to the teeth
• various sizes based on size of tooth
• winged and unwinged
• those with prongs are helpful in clamping partially
erupted teeth
Rubber dam clamp forceps: used to place and remove retainers
Dental floss: used to ligate clamps to the rubber dam frame
• prevents clamps from flying down patient’s
throat or in your face if it slips off the tooth
Scissors: Aid in the removal of the dam
Hole Punching
Each hole in the punch cutting table is associated with
specific teeth, as follows.
5: Anchor teeth
4: Molars
3: Premolars and cuspids
2: Maxillary incisors
1: Mandibular incisors
If any teeth in the operating field are missing or not in alignment, the holes for these teeth should be skipped or realigned and the operating field adjusted as necessary.
Exceptions to Use of Rubber Dam
- Patient phobic
- Respiratory problems: cold, asthma
- Extremely malposed teeth
- Broken down teeth
Removal of Rubber Dam
- Cut the interproximal rubber dam.
- Remove the rubber dam clamp with the rubber dam forceps. The clamp, rubber dam and rubber dam frame are removed as one unit.
Rectilinear Hand Instruments
Hatchets and Hoes – three-digit number
Ours are: Hatchet: 10-7-14
Hoe: 10-7-15
1st # = Blade width x 0.1mm
2nd # = Length of blade mm
3rd # = Angle of blade to handle ° centigrade
Margin trimmers – four digit number
Ours are: 10-97-7-14
1st # = Blade width x 0.1mm
2nd # =Angle of cutting edge to handle ° centigrade
3rd # = Length of blade mm
4th # = Angle of blade to handle ° centigrade
How to use
- Modified pen grasp
- Long side of blade is the cutting edge
- Keep blade parallel to long axis of tooth
- Small amounts of tissue only
- Scrape in one direction only
- Margin trimmers – scrape parallel to margin only
Tofflemire – order of placement/removal
- Insert band in holder, observe correct orientation of holder and band
- Place band over tooth, confirm placement in mirror
- Insert interdental wedge, (almost) always lingually (why?)
- Confirm adaptation of band to gingival margin in mirror
Order of removal
- Remove wedge
- Remove holder from band
- Remove band from tooth
Why do we use Matrix and Wedges?
Matrix band
• Support and give form to the restoration during placement
Wedge
- Adapt matrix band to gingival margin (prevent overhang)
- Separate teeth (compensate for thickness of matrix band)
Properties of the Ideal Restoration
- Restore Damaged Tooth
- Wear Resistance
- Fracture Resistance
- Bond to Tooth
- Bond to Self
- Smooth Surface
- Esthetic
- Low Conductivity
- Radiopaque